Pulsation Dampening System for High-Pressure Fluid Lines

ABSTRACT

Disclosed is an in-flow pulsation dampening system for high-pressure (e.g., 10K psi and higher) fluid lines. At high fluid flow pressures, the dampening system is a dual stage dampening system, responsive to low (e.g., when first charging the fluid line) and to very high-pressure pulsations. An external containment shell handles the full fluid flow pressures. One or more internal shells contain and handle the internal gas dampening system. The in-flow relationship of the gas dampening component assures that pressure differences between the internal gas handling system and the high-pressure fluid flow is always relatively small. This enables the gas handling components to be constructed of less robust material than the external shell (even though the gas system&#39;s internal pressure can equal that of the fluid flow), and be less susceptible to pressure failure.

CONTINUITY DATA

The present application claims the benefit of prior filed U.S.Provisional Patent Applications: Ser. No. 62/447,792 filed 18 Jan. 2017,Ser. No. 62/298,459 filed 23 Feb. 2016, and Ser. No. 62/286,367 filed 23Jan. 2016; to which prior applications the present application is aregular US national application, and which prior applications areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention is in the field of pipes and tubular conduits,including internal structures and end structures of the tubular member,and having fluid pressure compensators, e.g., accumulators or cushioningdevices (Class 138). Specifically, the present invention relate todevices with pressure compensators attachable to a pipeline fordampening pulsations in pressure caused by a quick-shutoff of flow or bythe non-uniform action of a pump system to maintain a more nearlyconstant pressure of the fluid (subclass 26). More specifically, thepresent invention relates to such devices having variable chambers(subclass 30), in which the chamber is of variable capacity by reason ofa slideable piston or plunger (subclass 31).

BACKGROUND OF THE INVENTION

An example use case for the present invention is in the field ofhigh-pressure hydraulic fracturing (aka: “fracing”), as used in the oilproduction industry. Fracing includes the use of high-pressure, positivedisplacement, pulsing pumps to deliver suspended sand fracing fluids tosubsurface areas containing oil deposits. The fracing process cracks theformation where oil resides and places sand in the fractures forimproved oil flow and volume to the wellbore.

Although utilizing the fracing process increases the cost of productionfor a well using it, the process can substantially increase theefficiency of the well's production. In times of high oil prices, theincrease of production efficiency exceeds the cost of the fracingprocess. Demand for fracing, along with horizontal drilling spurred aboom in US oil and natural gas production. However, in times of low oilprices, the increase in production efficiency does not offset the costof the fracing process for the well, and low producing wells areshut-in, rather than initiating a fracing operation. Even the largesthydraulic fracturing operations in the US have been forced todramatically cut costs in response to reduced demand for services. Withoil companies cutting and expecting to continue to cut more than 100billion dollars in spending globally, fracing expenditures are expectedto concomitantly fall as much as 35%. It has been reported that abouthalf of the hydraulic fracturing companies operating in the US would beclosed or sold by year-end 2015, because of falling oil prices andreduced oil company expenditure.

With a continuing poor outlook for a significant increase in oil pricesin near and mid-term future, solutions for reducing production expenses,including fracing costs, are expected to be a continued critical focus.One critically high cost common in the fracing industry is related toequipment failures, caused by the high-pressure, pulsating flow into thefracing piping. The high-pressure, pulsating flow results from themassive positive displacement pumps used to pump the fracing fluids intothe fracing piping. The pressure pulses slam the couplings, joints andfittings of the piping with thousands of pounds of force three hundred(300) times per minute causing failure of these fittings. Replacement ofhigh-pressure fracing equipment is very expensive. Failed fracingfixtures and pipe also results in costly downtime required to resourceand replace failed components before the production process cancontinue. Pumps, piping, fittings, and valves are all adversely affectedby the very high-pressure pulses from the massive positive displacementfracing pump systems. The industry has long been in search of meaningfulsolutions to the fracing iron failure problem. It would be seriouslybeneficial to the oil production industry, and hydraulic fracturingservices specifically, if a means for reducing fracing costs couldfinally be provided with a solution.

However, there are serious barriers to safe and successfulimplementation pulsation dampening on high-pressure pulsatile flowlines. One major barrier is to the use of “gas-cushioning” in pulsationdampeners. This is because in high-pressure applications (e.g.,pressures on the order of 20,000 psig), the very highly compressed gascan present a very real explosion threat and potential injury to nearbypersons and equipment. Another barrier that has long prevented theapplication of “gas-cushioning” in pulsation dampeners is thelimitations of gas-seals in the dampener apparatus to withstand and beproof against the high Δ_(p) (pressure differentials) typical ofhigh-pressure pulsatile flow systems. Also, in “gas-cushioning” typepulsation dampeners with moving interfaces (e.g., a sliding piston) thepressure differentials across barriers (e.g., walls) separating liquidand gaseous spaces can be distorted or caused to balloon under thepressure differences. This is a serious problem for maintainingliquid/gas seal integrity at a dampener's moving/sliding interfaces.

Reference Numerals  D Depth of the interior wall  L Length of Dampenerhousing  10 HP flow pulsation dampener  12 Dampener housing  14 Dampenerhousing end  14a Dampener housing 1st end  14b Dampener housing 2nd end 15 Dampener housing axis  16 High-pressure fluid flow line  17 FluidI/O port  17a Fluid inlet port  17b Fluid outlet port  20Housing-to-flow line adapter  22 Fluid flow thru-path  24 Non-flow fluidchamber  26 Liquid communication means  28 Dampener housing fluid space 30 Union  33 Union flange member  34 Union flange member (a&b)  36Flange fasteners  50 Damper canister  52 Canister housing  53 Canisterhousing axis  54 Canister interior space  55 Canister flange  56Canister opening  57 Canister rim  58 Canister interior wall  59Canister interior bulkhead  60 Piston stop ring  61 Fastener aperture 62 Stop ring fasteners  64 Through-flow spacer ring  66 Radiusstand-off  68 Ring fluid port  69 Canister piston stop shoulder  70Damper piston assembly  72 Damper piston  74 Damper piston head  75aPiston gas pressure surface  75b Piston fluid pressure surface  76Damper piston skirt  79 Piston ring channel  82 Wiper ring  90 Gas portfitting  92 Gas port  94 Gas valve  96 Gas port cover 102 Canister gasport

SUMMARY OF THE INVENTION

Pulsations from high-pressure, massive positive displacement can onlyeffectively be controlled through the use of gas to provide dampening or“cushioning”. The use of high-pressure gas presents safety and designchallenges. Gases under extreme high-pressure are, by their nature,explosive. Control of gases at pressures in excess of three thousand(3,000) psig requires extremely heavy wall containers and massiveflanges, when contained using conventional material. This inventionmanages both the safety and the heavy wall concerns to present a safeand manageable solution to the requirement for pulsation reduction inhigh-pressure systems.

Prior art pulsation dampeners typically have a gas bladder design. Theseprior art dampeners are generally low volume gas due to their limitedpressure of 3,000 psig or below. Higher pressures require higher volumesof compressed gas due to the significantly reduced space as the gas iscompressed for pulsation control service. Obviously, as the pressureincreases with the resultant increase in high-pressure gas volume,safety concerns dominate. This concern eliminates the use of singlevolume bladders. Until this invention, high-pressure dampeners were notavailable, as companies would not allow such equipment in vibrationservice. Additionally, the size and weight of these high volumedampeners has limited their use.

As stated, the typical single gas volume (bladder) has been the basisfor pulsation control for prior art at much lower pressures. Thisinvention embodies a new approach to the large gas volume by segmentingthe large gas volume into discrete, single volumes of gas enclosed incylinders. These cylinders are equipped with pistons and the pistonsmove vertically to compress the gas above and within the cylinder. Thegas-containing, piston-driven cylinders are then placed internally alongthe pulsation dampener housing. The pulsation dampener housing isdesigned to withstand full hydraulic pressure of the process. Thecylinders are designed, however, for only a minimum of 4,000 psig.

The pulsation dampener housing is designed with eccentric reducersgradually increasing housing diameter from the flow piping to a largediameter pulsation dampener housing where the gas cylinders reside. Thepulsation dampener housing is flanged for easy removal, inspection andreplacement of the pressure cylinders from the pulsation dampenerhousing. The gas cylinders are placed in the pulsation dampener housingin such a manner that the process fluid passes directly below everycanister as the flow enters, flows through and then exits the dampener.

At the initiation of the process, the spaces around the sealed gascanisters become fluid-packed. After the dampener becomes fluid-packed,flow continues below the gas cylinders as designed. At that point,pressure pulses from the massive positive displacement pumps aretransferred to all portions of the pulsation dampener housing and allexternal surfaces of the gas cylinders. Since the gas cylinders arepreloaded with gas to 4,000 psig, as the external pressure increases onthe gas cylinders, the differential pressure across the gas cylinderhousing decreases, further reducing any threats of cylinder damage andgas release. As the pressure equalizes at 4000 psig and then continuesto increase, the gas cylinder piston lifts due to the pressuredifferential across the piston. However, the pressure differentialacross the cylinder housing is now zero with full containment of the gaswithin the cylinder. The pulsation dampener housing is exposed only tothe hydraulic pressure, while the gas is secondarily contained instress-free gas cylinders. Further increases in pressure result inincreased hydraulic pressure to the pulsation dampener housing only.These further pressure increases in the system and on the gas cylindersonly serve to lift the gas cylinder pistons to maintain an internalpressure equal to the external pressure to the cylinders.

As the high-pressure positive displacement pumps reach the requiredsystem pressure, high-pressure, equipment-damaging pulses initiate. Aseach pressure pulse from the reciprocating pistons of the positivedisplacement pumps enter the pulsation dampener, the increase indampener housing pressure form the pulse causes the gas cylinder pistonsto react and rise, dampening the pulse and reducing it to manageablemagnitudes in the dampener. The magnitude of the pulse is dampened andthe fluid flow through the dampener continues under the pistons asdesigned. The pulses are effectively dampened by the action of thepiston movement to absorb the pulse in the gas volumes of the gascylinders. During operation, the maximum pressure across the gascylinders is around 250 psig, while the cylinders remove up to 3,000psig pressure magnitude of the pulses during operation. The very lowpressure of 250 psig offers little threat to the structural integrity ofthe cylinders designed to withstand 4,000 psig. During the high-pressurepumping process, the dampener housing is only exposed to a much saferlower hydraulic pressure.

After the high-pressure process completes, the hydraulic pressure isrelieved from the dampener housing. At that point, the gas cylinderpistons return to their original position at the start of thehigh-pressure process. Before, during and after, the gas cylinders arehoused in a two (2) inch thick housing further adding protection fromexposure to high-pressure gas release.

Suspended solids are difficult to manage due to plugging and fouling.This invention handles suspended solids by incorporating a design thatpromotes high velocity under the gas cylinders such that suspendedsolids simply pass through the dampener with little effect on thedampener operation. Special wiper seals protect the piston seals duringoperation. The small amounts of solids infiltrating the dampener housingduring the process initiation and the filling of the dampener with fluidsimply settle to the lower flow stream. Since the upper portion seeslittle or no flow, solids are not carried to the upper section of thedampener. The flow-through design provides excellent solids managementduring the dampening process.

The design includes high yield strength, hardened stainless steel usingpatented welding processes to reduce the required wall thickness for thepulsation dampener housing. Coupled with the flow-through design, thehardened stainless steel provides both excellent erosion (suspendedsolids) and corrosion resistance for improved and extended equipmentlife for the dampener and gas cylinders.

The gas cylinders are filled through a single aperture in the piston,which also houses a one-way check valve allowing the gas to flow intothe gas cylinder but restricting flow from the gas cylinder. The checkvalve is not a perfect seal, such that a gas inlet seal system isemployed to assure no decrease in pressure prior to deployment. Thecheck valve leakage also provides a method for depressurizing thecylinder. Depressurizing the gas cylinder is accomplished by removingthe gas inlet seal, and allowing the to leak down through the checkvalve.

This invention is designed to safely utilize high-pressure gas toprovide a “cushion” to the very high-pressure pulsation generated byhigh-pressure, pulse-generating pressure source such as positivedisplacement pumps.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side elevation schematic view of a preferred embodiment ofthe present high-pressure flow pulsation dampener.

FIG. 1B is a schematic perspective view of a series of high-pressureflow pulsation dampeners of the present invention.

FIG. 2A is a side elevation cross-sectional schematic view of thehigh-pressure flow pulsation dampener of FIG. 1A.

FIG. 2B is a bottom plan partial cut-away view of the high-pressure flowpulsation dampener of FIG. 1A.

FIG. 2C is an end-on cross-sectional schematic view of the high-pressureflow pulsation dampener of FIG. 1A.

FIGS. 3A and 3B are: (A) a side elevation schematic view and (B) abottom plan view of a damper canister of the present high-pressure flowpulsation dampener.

FIG. 4 is an exploded perspective view of components of a dampercanister of the present high-pressure flow pulsation dampener.

FIG. 5 is a side elevation cross-sectional schematic view of the pistonassembly of the present high-pressure flow pulsation dampener.

FIGS. 6A & 6B are: (A) a partial phantom perspective view of a dampercanister, and (B) a cross-sectional view of a damper canister showing analternative disposition of the gas port fitting.

FIG. 7A & FIG. 7B are: (A) a side elevation view, and a perspective viewof an alternative embodiment of the present high-pressure flow pulsationdampener apparatus.

FIG. 8 is an exploded perspective view of the HP flow pulsation dampenerapparatus of FIG. 7 showing a tandem damper canister in exploded view.

FIGS. 9A-9D are views of the canister housing of the tandem dampercanister for practice in the present apparatus.

FIGS. 10A-10D are various views of a damper piston for use in thepresent apparatus.

FIGS. 11A-11D are various view of a stop ring for practice in thepresent apparatus.

FIGS. 12A-12D are various view of a through-flow spacer ring forpractice in the present apparatus.

FIGS. 13A-13D are various view of a canister housing for practice withtandem damper canisters in the present apparatus.

FIGS. 14A-14D are various view of an inlet port type union flange forpractice in the present apparatus.

FIG. 15 is a cross-sectional view through a side elevation of a tandemdamper canister HP flow pulsation dampener apparatus of FIG. 7.

FIGS. 16A & 16B are partial cross-sectional (A) end view and (B) sideelevation view of single canister dampener housings disposed in a seriesin a HP fluid flow line to accomplish the present HP flow pulsationdampener apparatus.

DESCRIPTION OF THE INVENTION

Referring now to the drawings, the details of preferred embodiments ofthe present invention are graphically and schematically illustrated.Like elements in the drawings are represented by like numbers, and anysimilar elements are represented by like numbers with a different lowercase letter suffix.

The present pulsation dampener apparatus 10 is disclosed for use in aHydraulic Fracturing (“frac” or “fracing”) process. In use in a fracingprocess, the pulsation dampener apparatus 10 is installed inline withthe flow of the fracing fluid, and acts to dampen pressure pulses in thehigh-pressure fluid flow in the fracing fluid line 16. However, it is tobe noted that although the embodiments set forth herein use the fracingprocess as an example of a pumping system utilizing high-pressure,pulsatile fluid flow, the present apparatus can be practiced withsubstantially any such high-pressure, pulsatile fluid flow system todampen high-pressure pulsations . . . especially in such systemutilizing fluid suspensions and having abrasive properties. It isimportant to note that the exemplified fracing fluids process operatesat flow rates and line pressures using highly abrasive liquidsuspensions that can be corrosive as well. Line pressures on the orderof 12,000 psi and flow rates of over 30 mph are not unusual, all ofwhich is intended in the present invention. In major part, the pulsationdampener apparatus 10 includes: a dampener housing 12; housing-to-flowline adapters 20; a series of damper canisters 50 internally disposedinside the dampener housing 12; and union interfaces 30 for joining adampener housing end 14 to a housing-to-flow line adapter 20 or to thedampener housing end 14 of another dampener housing 12.

In the embodiments illustrated in FIG. 1A and FIG. 2, the dampenerhousing 12 of the pulsation dampener apparatus 10 is an elongated pipehaving two ends 14, with first-end 14 a shown as being directlyconnected (by welding) to a housing-to-flow line adapter 20, and asecond-end 14 b shown as being directly connected (by welding) to aunion interface 30. In the preferred embodiment illustrated, thehigh-pressure components, such as the dampener housing 12, areanticipated as being made of martensitic steel (e.g., SS-420). However,high-pressure metal/steel component fabrications currently available inthe field may also be used for practicing the present invention

FIGS. 2A-2C show internal structure of a dampener housing 12, whichincludes a fluid flow thru-path 22 and a non-flow fluid chamber(s) 24,both of which are disposed along the length L of the dampener housing12. Inside the pulsation dampener apparatus 10, and specifically insidethe dampener housing 12, the fluid flow thru-path 22 and the non-flowfluid chamber(s) 24 are in liquid communication with each other. Theliquid communication means 26 is adapted and disposed so that the flowrate of the fracing fluid in the fracing fluid line 16 is notsubstantially impacted. This is accomplished by having as close to theminimal actual fluid transfer as possible between the fluid flowthru-path 22 and the non-flow fluid chamber(s) 24. The minimal actualfluid transfer is that amount necessary to enable any gas trapped in thedampener housing 12 to be dissolved and eventually carried away. Thissetup also is adapted to allow the fluid pressure of the fluid flowthru-path 22 to be fully communicated the fluid in the non-flow fluidchamber(s) 24. This is an important feature of the present invention, asit directly impacts a safety benefit of the present invention, as willbe explained below. The liquid communication means 26 in the embodimentsillustrated is simply a plurality of through-holes in the structure orwall separating portions of the fluid flow thru-path 22 and the non-flowfluid chamber(s) 24.

A housing-to-flow line adapter 20 is used to adaptively connect one orboth ends 14 of the dampener housing 12 to a high-pressure fluid flowline 16 at the inlet port (pump side) 17 a of the high-pressure fluidflow line 16 or the outlet port (down-hole side) 17 b. As with thedampener housing 12, the housing-to-flow line adapter 20 is alsodesigned to so that the flow rate of the fluid in the high-pressurefluid line 16 is not substantially impacted.

The series of damper canisters 50 internally disposed inside thedampener housing 12 are the heart of the present high-pressure pulsationdampener apparatus 10. The series of damper canisters 50 is internallydisposed in the non-flow fluid chamber 24 of the dampener housing 12.Each damper canister 50 has its upper portion immersed in the fluid (andfluid pressure) of the non-flow fluid chamber 24. However, the bottom ofeach canister 50 is disposed so that it is exposed to the pressure andfluid flow of the thru-path 22.

Because the canister bottoms are in pressure communication with thefluid flow thru-path 22, each damper canister 50 is disposed to dampen aportion of a pressure change of the fluid in the fluid flow thru-path22. Additionally, because the canisters are initially gas pressurizedfrom about 2,500 to 5,000 psi, the series of canisters 50 in the housing12 distribute the risk of a catastrophic failure of the pressuredampening system over the total number of pressure vessels (dampercanister). This greatly reduces or eliminates the risk of a catastrophicfailure event from the failure of a single pressure vessel.

Union interfaces 30 are designed and used to accomplish unions in thepresent invention in a number of situations. For example, unioninterfaces 30 can be used to join an end 14 of a dampener housing 12 toa housing-to-flow line adapter 20 (see FIGS. 1A and FIG. 2), or to anend 14 of another dampener housing 12 (see FIG. 1B). A union interface30 has a flange member 33 connectable to another flange member 33 (e.g.,on the housing-to-flow line adapter 20), using flange fasteners 36.

The damper canisters 50 are intended for use in the present pulsationdampener apparatus 10 as a plurality of damper canisters 50 in series.See FIG. 2. It is the series of damper canisters 50 that cumulativelyaccomplish the dampening of the fluid pressure pulses in a high-pressurefluid flow line 16. That is to say that the amplitude of fluid pressurepulses at the fluid outlet port 17 b is lower than at the fluid inletport 17 a. In the embodiments illustrated, the damper canisters 50 inthe depicted series are all substantially identical in structure,operational specifications and function. However, they do not have tobe, and there are situations in which the series may not consist of ahomogeneous set of damper canisters 50. For example, an initial gascharge in some canisters may be lower than for other canisters in theseries set, to accomplish a more gradual onset of damping action uponstartup and initial fluid charging of the damper apparatus 10. Anassembled damper canister 50 is disposed to withstand an operatingenvironment having varying gas and fluid pressures up to 12,500 psi. Themajor components of the damper canisters 50 are all similar Each dampercanister 50 (FIGS. 3A & 3B) has a canister housing 52, a damper pistonassembly 70, a piston stop ring 60, and a gas port fitting 90, asillustrated in FIGS. 4 & 5 and FIGS. 6A & 6B.

The canister housing 52 is in the form of a high-pressure gas cylinder,open at one end. The canister housing 52 has a housing interior space 54and a cross-sectional housing opening 56 at the one open end. Theinterior wall 58 of the canister housing 52 is adapted to closelyreceive a piston assembly 70. The piston assembly is slideable along theinterior wall 56 from the rim 57 at the housing opening 56 to a depth Dof the interior wall 56. Though closely received in the cross-section ofthe housing opening 56 of the canister housing 52, the damper pistonassembly 70 is freely slideable along the depth D of the interior wall56 in response to a difference in pressure across the piston assembly70.

A stop ring 60 is fixable to the housing rim 57 at the housing opening56 of the canister housing 52. The stop ring 60 is fixed to the housingrim 57 with stop ring fastening means 62; which are threaded fastenersin the illustrated embodiment. The piston stop ring 60 is adapted toretain the damper piston assembly 70 slideably within the canisterhousing 52. The further adaptation of the piston stop ring 60 is notobvious and is important because of the high-pressure and fluidsuspension environment in which it operates. To use fracing fluid as afluid suspension example, fracing fluid is not only abrasive (because itcontains sand suspended in the fluid), the solids that form thesuspension can and do settle-out on horizontal surfaces, accumulate likeplaques, and can hinder/restrict travel of the piston. Therefore, thestructural cross-section of the top ring 60 and the features of itsinterface with the housing rim 57 and piston skirt 76 are adapted toavoid accumulating sand/suspension plaques. The canister housing 52,damper piston assembly 70 and stop ring 60 in combination are adapted tocontain a gas in the housing interior space 54 at continuously varyingpressures of up to 12,500 psi, to accomplish the present damper canister50.

The piston assembly 70 comprises a damper piston 72 having a damperpiston head 74 portion and a damper piston skirt 76 portion. The pistonhead 74 portion has a gas pressure surface 75 a and a fluid pressuresurface 75 b. The piston skirt 76 portion has at least one piston ringchannel 79, within each of which a piston ring 82 is received. A firstpiston ring 82 is a gas/fluid sealing ring. A sealing type piston ring82 is biased by the ring channel 79 to form a slideable gas/fluidpressure seal between the piston skirt 76 and the interior wall 56 ofthe canister housing 52. Other rings may also be provided for sealingand/or particle wiping. The for example, in another embodiment (notshown) the piston skirt 76 has two ring channels 79 for mounting agas/fluid sealing ring, and also a wiper ring between the gas/fluidsealing ring and the frac fluid. The wiper ring is adapted to preventsand or suspension material from impacting the gas/fluid sealing ring.The piston assembly 70 is slideable within the canister housing 52 inresponse to a sufficient pressure difference between the gas pressurewithin the housing interior space 54 of the damper canister 50 and thefluid pressure of the fluid flow thru-path 22 outside of the dampercanister 50.

Additionally, the damper piston head 74 portion of the damper piston 72has a gas port fitting 90. The gas port fitting 90 is adapted to providea sealable through-port between the gas pressure surface 75 a and thefluid pressure surface 75 b of the piston head 74. The gas port fittingenables the housing interior space 54 to receive and contain a gascharge to bias the housing interior space 54 at an initial gas pressure.The gas port fitting 90 component of the damper piston 72 has a gasthrough-port 92 between the gas pressure surface 75 a and the fluidpressure surface 75 b of the piston head 74. A normally closed gas checkvalve 94 provides a means to charge the housing interior space 54 with agas, such as nitrogen, and prevents the gas from escaping. A gas portcover 96 protects the gas valve 94 from the fluid at the fluid pressuresurface 75 b of the piston head 74, and further seals the gas portfitting to prevent gas from leaking out of the canister housing 52.Although illustrated as a component of the damper piston 72 in FIGS. 4 &5, the gas port fitting 90 may be disposed elsewhere on a dampercanister 50 as selectable by on of skill in the art, see FIGS. 6A & 6B.

In an alternative embodiment for dampening pressure pulsations in ahigh-pressure fluid flow line/conduit, the pulsation dampener apparatus10 a of the present invention can be configured as illustrated in FIGS.7A & 7B. In this embodiment, the dampener housing 12 a is also asubstantially cylindrical tube having a dampener interior fluid space 28along an axis 15 of length L of the dampener housing 12 a. The dampenerhousing 12 a has a first end 14 a open and a second end 14 c closed. Thefirst end 14 a is shown in fluid communication with the high-pressurefluid flow line 16 via flange members 33 & 34 a of a pipe union 30. SeeFIGS. 14A-14D for an example of a flow-through union flange member 34 a.The second end 14 c is closed with a flange member 33 and a flange plate34 b. However, if desired the second end 14 c of the pulsation dampenerapparatus 10 a may be connected to the fluid flow line 16 or in seriesto another pulsation dampener apparatus 10 a by replacing the flangeplate 34 b with an appropriate flange member (e.g., 34 a). Also see FIG.8 and FIGS. 13A-13C.

As exemplified in FIGS. 9A-9D, a dampener housing 12 a contains at leastone “tandem” damper gas canister 50 a. The “tandem” feature of thedamper gas canister 50 a derives from the gas canister 50 a housing twoseparate damper piston assemblies 70 a. The gas canister 50 a has acanister axis 53, and one or more tandem damper gas canisters 50 a arereceived within the dampener housing 12 a with its canister axis 53parallel to the housing axis 15. The damper gas canisters 50 a are inpressure communication with the interior fluid space 28 of the dampenerhousing 12 a. The canister housing 52 a of a tandem damper gas canister50 a is in the form of a high-pressure gas cylinder having a housinginterior space 54 and a cross-sectional housing opening 56 at each end,and an interior wall 58. The interior wall 58 is adapted to slideablyreceive a damper piston assembly 70 a along a depth D of the interiorwall 58.

A damper piston assembly 70 a is closely received within thecross-sectional opening 56 of each end of the canister housing 52 a. Inthe embodiments illustrated, the damper piston assemblies 70 a arefreely slideable along the depth D of the interior wall 58 of thecanister housing 52 a. As exemplified in FIGS. 10A-10D, the damperpiston 72 of the piston assembly 70 a has a piston head 74 portion and apiston skirt 76 portion. The piston head 74 portion of the damper piston72 has a gas pressure surface 75 a and a fluid pressure surface 75 b.The piston skirt 76 portion has at least one piston ring channel 79.Piston ring channels each will contain a wiper ring 82. Wiper rings 82are biased by the ring channel 79 to form a slideable gas/fluid pressureseal between the piston skirt 76 and the interior wall 58 of thecanister housing 52 a. The piston assembly 70 a is slideable in onedirection or another within the canister housing 52 a in response to asufficient pressure difference between the gas pressure within thecanister interior space 54 and the fluid pressure of the fluid containedwithin the dampener housing interior fluid space 28 of said pulsationdampener apparatus 10 a. That is, when there is a Δ_(Press) across thegas pressure surface 75 a and the fluid pressure surface 75 b of thepiston head 74. The structure of the piston head 74 provides a pressuredifferential energized seal system substantially similar to thatdescribed for the piston head 74 of FIG. 5. Wherein, the deformation ofthe piston head 74 from the pressure differential across the piston headsurfaces 75 a & 75 b causes the dome of the piston head 74 to flatten,thus further biasing the seal portion of the piston assembly radiallyand toward the canister wall 58, effecting an improved seal.

As illustrated in the figures, this embodiment of the damper piston head74 portion of the damper piston 72 has a gas port fitting 90. Althoughillustrated as a component of the damper piston 72 in FIGS. 4 & 5, thegas port fitting 90 may be disposed elsewhere on a damper canister 50 asselectable by on of skill in the art, see FIGS. 6A & 6B. The gas portfitting 90 is adapted to provide a sealable through-port between the gaspressure surface 75 a and the fluid pressure surface 75 b of the pistonhead 74. The gas port fitting 90 is provided to enable the canisterinterior space 54 to receive and contain a gas charge to bias thecanister interior space 54 at an initial gas pressure, e.g., at 4,000psi. In the embodiment exemplified in FIGS. 10A-10D, the gas portfitting 90 is substantially the same as that depicted in FIG. 5.

As shown in FIGS. 11A-11D, a stop ring 60 is fixable to the housing rim57 at each housing opening 56, using such means as exemplified in FIG.4, or by other means as selected by the skilled artisan and adapted toretain the damper piston assembly 70 a slideably within the canisterhousing 50. The canister housing 52 a, damper piston assembly 70 a andstop ring 60 in combination are adapted to contain a gas in the housinginterior space 54 at continuously varying pressures up to 12,000 psi toprovide the present damper canister 50 a.

As illustrated in FIG. 15, the present pressure pulsation dampenerapparatus 10 a is adapted to receive a plurality of tandem damper gascanisters 50 a in series within the dampener housing 12 a. In thisembodiment, all of the tandem canister axes 53 are parallel (andcoaxial) to the dampener housing axis 15. A through-flow spacer ring 64(see FIGS. 12A-12D) is disposed between adjacent tandem damper gascanisters 50 a. The through-flow spacer rings 64 enable fluid (from thehigh-pressure fluid flow line 16) to be communicated throughout thehousing fluid space 28 of the dampener housing 12 a, and thence to thepiston fluid pressure surfaces 75 b of the piston heads 74 betweenadjacent tandem damper gas canisters 50 a.

In another alternative embodiment exemplified in FIGS. 16A & 16B, thepresent pressure pulsation dampener apparatus 10 a may be configured asa single canister dampener housings 50 c disposed in a series in ahigh-pressure fluid flow line 16 to accomplish the present invention.

Attached as an Appendix is an engineering & design report exemplifyingmaterials and design considerations for various embodiments of thepresent invention. The report is included herein by reference.

While the above description contains many specifics, these should not beconstrued as limitations on the scope of the invention, but rather asexemplifications of one or another preferred embodiment thereof Manyother variations are possible, which would be obvious to one skilled inthe art. Accordingly, the scope of the invention should be determined bythe scope of the appended claims and their equivalents, and not just bythe embodiments.

What is claimed is:
 1. A pulsation dampener apparatus (10) for dampeningpressure pulses in a high-pressure fluid flow line (16), the pulsationdampener apparatus (10) comprising: a dampener housing (12), thedampener housing (12) substantially being an elongated pipe having twoends (14) a first-end (14 a) and a second-end (14 b), and internallyhaving a fluid flow thru-path (22) and a non-flow fluid chamber (24)both along a length (L) of the dampener housing (12), the dampenerhousing (12) in liquid communication with the fluid flow thru-path (22);a housing-to-flow line adapter (20) adapted to connect the ends (14) ofthe dampener housing (12) to said high-pressure fluid flow line (16); aseries of damper canisters (50) internally disposed in the non-flowfluid chamber (24) of the dampener housing (12), the damper canisters(50) immersed in a fluid in the non-flow fluid chamber (24) and eachdamper canister (50) in pressure communication with the fluid flowthru-path (22) and adapted to dampen a portion of a pressure change ofthe fluid in the fluid flow thru-path (22); and A union interface (30)adapted to join one end (14) of the dampener housing (12) to ahousing-to-flow line adapter (20), the union interface (30) having aflange member (33) connectable to another flange member (33) on thehousing-to-flow line adapter (20) using flange fasteners (36), thecombination when installed in the high-pressure fluid flow line (16),providing dampening of pressure pulsations of the fluid in thehigh-pressure fluid flow line (16).
 2. A pulsation dampener apparatus(10) for dampening pressure pulses in a high-pressure fluid flow line(16) of claim 1, wherein the fluid is a fracing fluid.
 3. A dampercanister (50) for use in a pulsation dampener apparatus (10) fordampening fluid pressure pulses in a fluid in a high-pressure fluid flowline (16), the damper canister (50) comprising: a canister housing (52)in the form of a high-pressure gas cylinder, the canister housing (52)having a housing interior space (54) and a cross-sectional housingopening (56) at one end, and an interior wall (58) adapted to slideablyreceive a piston assembly (70) along a depth (D) of the interior wall(58); a damper piston assembly (70) is closely received in thecross-sectional opening (56) of the canister housing (52), the pistonassembly (70) is freely slideable along the depth (D) of the interiorwall (58) of the canister housing (52); a stop ring (60) is fixable to ahousing rim (57) at the housing opening (56) with a stop ring fasteningmeans (62) and adapted to retain the damper piston assembly (70)slideably within the canister housing (50); and the canister housing(52), damper piston assembly (70) and stop ring (60) in combinationadapted to contain a gas in the housing interior space (54) atcontinuously varying pressures up to 12,000 psi to provide said dampercanister (50).
 4. The damper canister (50) of claim 3, wherein thepiston assembly (70) comprises: a damper piston (72) having a damperpiston head (74) portion and a damper piston skirt (76) portion; thepiston head (74) portion having gas pressure surface (75 a) and a fluidpressure surface (75 b); the piston skirt (76) portion, having a pistonring channel (79) within which a wiper ring (82) is received; the wiperring (82) being biased by the ring channel (79) to form a slideablegas/fluid pressure seal between the piston skirt (76) and the interiorwall (58) of the canister housing (52); and the piston assembly (70)being slideable within the canister housing (52) in response to asufficient positive pressure difference between a gas pressure withinthe canister interior space (54) and a fluid pressure of a fluid flowthru-path (22) of said pulsation dampener apparatus (10).
 5. The dampercanister (50) of claim 3, wherein the piston assembly (70) furthercomprises the damper piston head (74) portion of the damper piston (72)having a gas port fitting (90) adapted to provide a sealablethrough-port between the gas pressure surface (75 a) and the fluidpressure surface (75 b) of the piston head (74) to enable the housinginterior space (54) to receive and contain a gas charge to bias thehousing interior space (54) at an initial gas pressure.
 6. The pistonassembly (70) of claim 5 wherein gas port fitting (90) of the damperpiston (72) comprises: a gas through-port (92) between the gas pressuresurface (75 a) and the fluid pressure surface (75 b) of the piston head(74); a normally closed gas valve (94) providing a means to charge thehousing interior space (54) with a gas; and a gas port cover protectingthe gas valve (94) from a fluid at the fluid pressure surface (75 b) ofthe piston head (74).
 7. The piston assembly (70) of claim 5 wherein thestructure provides a pressure differential energized seal systemdesigned to maintain a constant clearance between the piston assembly(70) and the canister wall, with the deformation of the piston from theinternal gas pressure causes the piston assembly (70) to flatten, thusfurther biasing the seal portion of the piston assembly radially andtoward the canister wall, effecting an improved seal.
 8. A pressurepulsation dampener apparatus for use in a HP fluid flow line, theapparatus comprising: a dampener housing (12 a) substantially being acylindrical tube having a dampener interior fluid space (28) along adampener housing axis (15) of length (L), a first open end (14 a) is influid communication with said HP fluid flow line (16) via a union (30),and a second closed end (14 c); at least one tandem damper gas canister(50 a) having a canister axis (53), the tandem damper gas canister (50a) received within the dampener housing (12 a) with its canister axis(53) parallel to the housing axis (15), the damper gas canister (50 a)in pressure communication with the interior fluid space (28) of thedampener housing (12 a).
 9. The apparatus of claim 8, wherein the tandemdamper gas canister (50 a) comprises: a canister housing (52 a) in theform of a high-pressure gas cylinder, the canister housing (52 a) havinga housing interior space (54) and a cross-sectional housing opening (56)at each end, and an interior wall (58) adapted to slideably receive apiston assembly (70 a) along a depth (D) of the interior wall (58); adamper piston assembly (70 a) is closely received in the cross-sectionalopening (56) at each end of the canister housing (52 a), the damperpiston assemblies (70 a) are freely slideable along the depth (D) of theinterior wall (56) of the canister housing (52 a); a stop ring (60) isfixable to a housing rim (57) at each housing opening (56) with stopring fastening means (62) and adapted to retain the damper pistonassembly (70 a) slideably within the canister housing (50); and thecanister housing (52 a), damper piston assembly (70 a) and stop ring(60) in combination adapted to contain a gas in the housing interiorspace (54) at continuously varying pressures up to 12,000 psi to providesaid damper canister (50 a).
 10. The tandem damper gas canister (50 a)of claim 9, wherein the piston assembly (70 a) comprises: a damperpiston (72) having a damper piston head (74) portion and a damper pistonskirt (76) portion; the piston head (74) portion having gas pressuresurface (75 a) and a fluid pressure surface (75 b); the piston skirt(76) portion, having at least one piston ring channel (79) within eachof which ring channels (79) a wiper ring (82) is received; the wiperring (82) being biased by the ring channel (79) to form a slideablegas/fluid pressure seal between the piston skirt (76) and the interiorwall (58) of the canister housing (52 a); and the piston assembly (70 a)being slideable within the canister housing (52 a) in response to asufficient pressure difference between a gas pressure within thecanister interior space (54) and a fluid pressure of a fluid containedwithin the dampener housing interior fluid space (28) of said pulsationdampener apparatus (10 a).
 11. The damper canister (50 a) of claim 9,wherein the piston assembly (70 a) further comprises the damper pistonhead (74) portion of the damper piston (72) having a gas port fitting(90) adapted to provide a sealable through-port between the gas pressuresurface (75 a) and the fluid pressure surface (75 b) of the piston head(74) to enable the canister interior space (54) to receive and contain agas charge to bias the canister interior space (54) at an initial gaspressure.
 12. The piston assembly (70 a) of claim 11 wherein gas portfitting (90) of the damper piston (72) comprises: a gas through-port(92) between the gas pressure surface (75 a) and the fluid pressuresurface (75 b) of the piston head (74); a normally closed gas valve (94)providing a means to charge the housing interior space (54) with a gas;and a gas port cover protecting the gas valve (94) from a fluid at thefluid pressure surface (75 b) of the piston head (74).
 13. The pistonassembly (70 a) of claim 11, wherein the structure of the piston (72)provides a pressure differential energized seal system designed tomaintain a constant clearance between the piston assembly (70) and thecanister wall, with the deformation of the piston head (74) from thepressure differential across the piston head surfaces (75 a & 75 b)causes the piston head (74) to flatten, thus further biasing the sealportion of the piston assembly radially and toward the canister wall,effecting an improved seal.
 14. The pressure pulsation dampenerapparatus of claim 8, wherein the dampener housing (12 a) is adapted toreceive a plurality of tandem damper gas canisters (50 a) within thedampener housing (12 a) with all the canister axis (53) parallel to thedampener housing axis (15), and further having a through-flow spacerring (64) disposed between adjacent tandem damper gas canisters (50 a)for communicating a fluid pressure of the dampener housing interiorfluid space (28) of the dampener housing (12 a) to the piston fluidpressure surface (75 b) of the piston head (74) between adjacent tandemdamper gas canisters (50 a).